The Collaborative International Dictionary of English v.0.48:

Quintuple \Quin"tu*ple\, a. [L. quintus fifth: cf. F. quintuple,
   L. quintuplex. Cf. Quadruple.]
   Multiplied by five; increased to five times the amount;
   fivefold.
   [1913 Webster]

   Quintuple time (Mus.), a time having five beats in a
      measure. It is seldom used.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quintuple \Quin"tu*ple\, v. t. [imp. & p. p. Quintupled; p.
   pr. & vb. n. Quintupling.] [Cf. F. quintupler.]
   To make fivefold, or five times as much or many.
   [1913 Webster]

WordNet (r) 3.0 (2006):

quintuple
    adj 1: having five units or components [syn: quintuple,
           fivefold, five-fold]
    n 1: a set of five similar things considered as a unit [syn:
         quintet, quintette, quintuplet, quintuple]
    v 1: increase fivefold; "The population of China quintupled"